A Data-Driven Latent Variable Approach to Validating the Research Domain Criteria Framework.

Despite the widespread use of the Research Domain Criteria (RDoC) framework in psychiatry and neuroscience, recent studies suggest that the RDoC is insufficiently specific or excessively broad relative to the underlying brain circuitry it seeks to elucidate. To address these concerns of the RDoC framework, our study employed a latent variable approach, specifically utilizing bifactor analysis. We examined a total of 84 whole-brain task-based fMRI (tfMRI) activation maps from 19 studies with a total of 6,192 participants. Within this set of 84 maps, a curated subset of 37 maps with a balanced representation of RDoC domains constituted the training set of our analysis, and the remaining held-out maps formed the internal validation set. External validation was performed with 36 peak coordinate activation maps from Neurosynth, using terms of RDoC constructs as seeds for topic meta-analysis. Our results indicate that a bifactor model with a task-general domain and splitting the cognitive systems domain into sub-domains better fits the current corpus of tfMRI data than the current RDoC framework. Our data-driven validation supports revising the RDoC framework to accurately reflect underlying brain circuitry.

Antigenic and genetic evolution of equine influenza A (H3N8) virus from 1968 to 2007.

Equine influenza virus is a major respiratory pathogen in horses, and outbreaks of disease often lead to substantial disruption to and economic losses for equestrian industries. The hemagglutinin (HA) protein is of key importance in the control of equine influenza because HA is the primary target of the protective immune response and the main component of currently licensed influenza vaccines. However, the influenza virus HA protein changes over time, a process called antigenic drift, and vaccine strains must be updated to remain effective. Antigenic drift is assessed primarily by the hemagglutination inhibition (HI) assay. We have generated HI assay data for equine influenza A (H3N8) viruses isolated between 1968 and 2007 and have used antigenic cartography to quantify antigenic differences among the isolates. The antigenic evolution of equine influenza viruses during this period was clustered: from 1968 to 1988, all isolates formed a single antigenic cluster, which then split into two cocirculating clusters in 1989, and then a third cocirculating cluster appeared in 2003. Viruses from all three clusters were isolated in 2007. In one of the three clusters, we show evidence of antigenic drift away from the vaccine strain over time. We determined that a single amino acid substitution was likely responsible for the antigenic differences among clusters.

Vaccines and viral antigenic diversity.

Antigenic diversity among ribonucleic acid (RNA) viruses occurs as a result of rapid mutation during replication and recombination/reassortment between genetic material of related strains during co-infections. Variants which have a selective advantage in terms of ability to spread or to avoid host immunity become established within populations. Examples of antigenically diverse viruses include influenza, foot and mouth disease (FMD) and bluetongue (BT). Effective vaccination against such viruses requires surveillance programmes to monitor circulating serotypes and their evolution to ensure that vaccine strains match field viruses. A formal vaccine strain selection scheme for equine influenza has been established under the auspices of the World Organisation for Animal Health (OIE) based on an international surveillance programme. A regulatory framework has been put in place to allow rapid updating of vaccine strains withoutthe need to provide full registration data for licensing the updated vaccine. While there is extensive surveillance of FMD worldwide and antigenic and genetic characterisation of isolates, there is no formal vaccine strain selection system. A coordinated international effort has been initiated to agree harmonised approaches to virus characterisation which is aimed at providing the basis for an internationally agreed vaccine matching system for FMD supported by the OIE. The emergence and spread of BT in Europe have resulted in an intensification of vaccine evaluation in terms of safety and efficacy, particularly cross-protection within and between serotypes. The most important requirement for producing vaccines against viruses displaying antigenic diversity is a method of measuring antigenic distances between strains and developing an understanding of how these distances relate to cross-protection. Antigenic cartography, a new computational method of quantifying antigenic distances between strains has been applied to human and equine influenza to examine the significance of viral evolution in relation to vaccine strains. This method is highly applicable to other important pathogens displaying antigenic diversity, such as FMD.

Use of DNA and recombinant canarypox viral (ALVAC) vectors for equine herpes virus vaccination.

In this study, experimental canarypox virus (ALVAC) and plasmid DNA recombinant vaccines expressing the gB, gC and gD glycoproteins of EHV-1 were assessed for their ability to protect conventional ponies against a respiratory challenge with EHV-1. In addition, potential means of enhancing serological responses in horses to ALVAC and DNA vaccination were explored. These included co-administration of the antigen with conventional adjuvants, complexation with DMRIE-DOPE and co-expression of the antigen along with equine GM-CSF. Groups of EHV primed ponies were vaccinated twice intra-muscularly with one dose of the appropriate test vaccine at an interval of 5 weeks. Two to 3 weeks after the second vaccination, ponies were infected intra-nasally with the virulent Ab4 strain of EHV-1 after which they were observed clinically and sampled for virological investigations. The results demonstrated that DNA and ALVAC vaccination markedly reduced virus excretion after challenge in terms of duration and magnitude, but failed to protect against cell-associated viremia. Noteworthy was the almost complete absence of virus excretion in the group of ponies vaccinated with ALVAC-EHV in the presence of Carbopol adjuvant or DNA plasmid formulated with aluminium phosphate. The administration of the DNA vaccine in the presence of GM-CSF and formulated in DMRIE-DOPE and of the ALVAC vaccine in the presence of Carbopol adjuvant significantly improved virus neutralising antibody responses to EHV-1. These findings indicate that DNA and ALVAC vaccination is a promising approach for the immunological control of EHV-1 infection, but that more research is needed to identify the immunodominant protective antigens of EHV-1 and their interaction with the equine immune system.

Description of the outbreak of equine influenza (H3N8) in the United Kingdom in 2003, during which recently vaccinated horses in Newmarket developed respiratory disease.

Between March and May 2003, equine influenza virus infection was confirmed as the cause of clinical respiratory disease among both vaccinated and unvaccinated horses of different breeds and types in at least 12 locations in the UK. In the largest outbreak, 21 thoroughbred training yards in Newmarket, with more than 1300 racehorses, were affected, with the horses showing signs of coughing and nasal discharge during a period of nine weeks. Many of the infected horses had been vaccinated during the previous three months with a vaccine that contained representatives from both the European (A/eq/Newmarket/2/93) and American (A/eq/Newmarket/1/93) H3NN8 influenza virus lineages. Antigenic and genetic characterisation of the viruses from Newmarket and elsewhere indicated that they were all closely related to representatives of a sublineage of American viruses, for example, Kentucky/5/02, the first time that this sublineage had been isolated in the uk. In the recently vaccinated racehorses in Newmarket the single radial haemolysis antibody levels in acute sera appeared to be adequate, and there did not appear to be significant antigenic differences between the infecting virus and A/eq/Newmarket/1/93, the representative of the American lineage virus present in the most widely used vaccine, to explain the vaccine failure. However, there was evidence for significantly fewer infections among two-year-old horses than older animals, despite their having similar high levels of antibody, consistent with a qualitative rather than a quantitative difference in the immunity conveyed by the vaccination.

A phenome-wide examination of neural and cognitive function.

This data descriptor outlines a shared neuroimaging dataset from the UCLA Consortium for Neuropsychiatric Phenomics, which focused on understanding the dimensional structure of memory and cognitive control (response inhibition) functions in both healthy individuals (130 subjects) and individuals with neuropsychiatric disorders including schizophrenia (50 subjects), bipolar disorder (49 subjects), and attention deficit/hyperactivity disorder (43 subjects). The dataset includes an extensive set of task-based fMRI assessments, resting fMRI, structural MRI, and high angular resolution diffusion MRI. The dataset is shared through the OpenfMRI project, and is formatted according to the Brain Imaging Data Structure (BIDS) standard.

Inflammatory airway disease, nasal discharge and respiratory infections in young British racehorses.

REASONS FOR PERFORMING STUDY: Respiratory disease is important in young Thoroughbred racehorses, but the variation in the rates of occurrence between different ages and training groups has not been characterised. OBJECTIVES: To determine the rates of respiratory disease, particularly inflammatory airway disease (IAD), as well as evidence of infection, and their variation between age and group. METHODS: Horses were examined monthly in 7 British flat training yards over a 3 year period. IAD was defined as increased mucus in the trachea with increased proportions of neutrophils in tracheal wash samples. Frequencies of disease outcomes were estimated from the data. RESULTS: The prevalence of IAD was 13.8% and the incidence was 8.9 cases/100 horses/month. Rates varied with training and age groups, decreasing in older animals. The prevalence of nasal discharge (ND) was 4.1%. Rates of bacterial isolation were more common than viral infections. The incidence and prevalence of several bacterial species decreased with age. CONCLUSIONS: IAD and ND were common in young racehorses, varying significantly between training groups and decreasing with age, consistent with infection playing a role in aetiology. POTENTIAL RELEVANCE: The high prevalence of IAD in 2-year-old horses in Britain suggests that routine endoscopic examination may be helpful in providing early diagnosis and appropriate therapy. The transmission of bacteria and viruses within and between groups of young animals and the role of infection, stable environment and factors inherent to each horse, including their genetic make-up, in the multifactorial aetiology of the disease all merit further study.

The effects of strain heterology on the epidemiology of equine influenza in a vaccinated population.

We assess the effects of strain heterology (strains that are immunologically similar but not identical) on equine influenza in a vaccinated population. Using data relating to individual animals, for both homologous and heterologous vaccinees, we estimate distributions for the latent and infectious periods, quantify the risk of becoming infected in terms of the quantity of cross-reactive antibodies to a key surface protein of the virus (haemagglutinin) and estimate the probability of excreting virus (i.e. becoming infectious) given that infection has occurred. The data suggest that the infectious period, the risk of becoming infected (for a given vaccine-induced level of cross-reactive antibodies) and the probability of excreting virus are increased for heterologously vaccinated animals when compared with homologously vaccinated animals. The data are used to parameterize a modified susceptible, exposed, infectious and recovered/resistant (SEIR) model, which shows that these relatively small differences combine to have a large effect at the population level, where populations of heterologous vaccinees face a significantly increased risk of an epidemic occurring.

Expression cloning and antigenic analysis of the nucleocapsid protein of equine arteritis virus.

A series of recombinant fusion proteins derived from equine arteritis virus (EAV) open reading frame (ORF) 7 have been used to define the immunoreactive region of the viral nucleocapsid (N) protein. Reactivities of recombinant N fusion proteins with post-infection equine sera in immunoblots and ELISAs indicate that the major nucleocapsid protein epitope is located within amino acid residues 1-69. In ELISAs two recombinant nucleocapsid fusion proteins containing residues 1-69 (rN1-69) and 1-28 (rN1-28) discriminated between pre- and post-infection, and pre- and post-vaccination serum samples. Additionally rN1-69 and rN1-28 detected seroconversions following vaccination with a killed virus preparation, even in the absence of a detectable virus neutralising response. Although a good correlation existed between virus neutralising antibody and rN1-69 ELISA positive values in post-infection sera, all the rN proteins failed to induce any virus neutralising response in immunised rabbits.

Equid herpesvirus-induced immunosuppression is associated with lymphoid cells and not soluble circulating factors.

A paresis isolate of equid herpesvirus 1 (EHV1, Ab4/8) and a plaque-purified virus derived from it (EHV1, Ab4/13), induced long-term suppression of both mitogenic and antigen-specific lymphocyte proliferations in adult outbred ponies. Peripheral blood mononuclear cells (PBMC) taken from a pony after EHV1 infection suppressed the in vitro function of normal cells but serum did not. This showed that the observed immune suppression was associated with circulating PBMC and/or their products rather than circulating soluble factors such as antigen or immune complexes. The results suggested that productive infection of lymphocytes by EHV1 was unlikely to result in the observed in vitro effects. Moreover, prostaglandin release from monocytes was not likely to have caused the observed suppression, because lymphocyte responsiveness was not restored in the presence of indomethacin.

Rapid detection of equine herpesvirus type-1 antigens in nasal swab specimens using an antigen capture enzyme-linked immunosorbent assay.

An antigen capture enzyme-linked immunosorbent assay (ELISA) was developed for the detection of equine herpesvirus type-1 (EHV-1) antigens in nasal swab specimens. The test was designed as a solid phase, amplified sandwich assay in which an EHV-1 specific monoclonal antibody was used to capture virus antigen and polyclonal antisera used to detect antigen bound to the test plates. Eight monoclonal antibodies were tested for their ability to capture virus antigen and one was selected for routine use. The sensitivity and specificity of the ELISA was compared with that of virus isolation using swabs from ponies which were experimentally infected with EHV-1. Of 72 nasal swabs collected, 32 were found to be positive by both virus isolation (VI) and ELISA, a further 15 samples were positive by VI alone, but none of the samples were positive by ELISA and negative by VI. This yielded an overall assay sensitivity of 68% and specificity of 100%. The assay proved useful for diagnosis since virus antigen was detected during the first four days post-infection which corresponded to the acute phase of disease when some clinical symptoms were apparent. In addition, the assay could be completed within one day when antibody coated plates were available.

Detection of influenza nucleoprotein antigen in nasal secretions from horses infected with A/equine influenza (H3N8) viruses.

An antigen capture indirect enzyme linked immunosorbent assay (ELISA) was developed to detect influenza nucleoprotein antigen in nasal secretions from horses infected with A/equine/H3N8 viruses. Results from this assay were compared with conventional virus isolation in embryonated hens eggs.

Development of PCR assays to detect genetic variation amongst equine herpesvirus-1 isolates as an aid to epidemiological investigation.

A search for variable restriction sites has been carried out for equine herpesvirus-1 (EHV-1) in an attempt to develop markers which can be used to group epidemiologically related viruses into groups, and to learn more about the dynamics of EHV-1 disease. Crude viral DNA extracts of EHV-1, prepared by Hirt extraction, were digested with AluI, HaeIII, or RsaI, and Southern blotted following electrophoresis. DNA fingerprints, produced by probing the Southern blots with the EHV-1 EcoR1-I fragment, separated 56 isolates into 16 groups. The variable sites within the EcoR1-I fragment were mapped approximately using fragments from within EcoR1-I, and the precise location of the variable sites determined from the DNA sequence of this fragment. Oligonucleotide primers flanking the variable sites were synthesized, and used in PCR assays to detect variable fragments. The AluI variable fragment was found to result from the presence or absence of a single AluI site. In contrast, the variable bands seen with HaeIII and RsaI, resulted from variation in the copy number of two tandemly repeated sequences, one of which had not previously been recognized. In addition, HaeIII digests of EHV-1 isolates probed with the glycoprotein B (gB) gene of EHV-1 also separated isolates into two groups. The variable HaeIII site was mapped towards the 5'-end of the gB gene and a PCR assay established. The distribution of the variable AluI site within the EcoR1-I fragment and the HaeIII site within the gB gene were estimated on a large number of clinical isolates using PCR on unpurified viral tissue culture medium. Both sites had a good distribution and together with additional variable sites should provide the basis for the rapid DNA fingerprinting of EHV-1 isolates.

Development and evaluation of an ELISA using recombinant fusion protein to detect the presence of host antibody to equine arteritis virus.

A recombinant glutathione-S-transferase fusion protein expressing amino acids 55-98 of equine arteritis virus (EAV) GL (rGL 55-98) was tested in an ELISA for its ability to detect serum antibodies to EAV. Host antibodies induced following EAV infection bound the recombinant antigen by ELISA. The ELISA specificity and sensitivity were determined with a panel of equine sera including postinfection and postvaccination samples. A good correlation existed between EAV neutralizing antibody titers and ELISA absorbance values (r = 0.827). The sensitivity and specificity of the ELISA were 99.6 and 90.1%, respectively, compared with EAV neutralization test and the recombinant antigen did not crossreact in ELISA with equine sera directed against other common equine respiratory viruses. Three post-EAV infection equine sera raised against different EAV isolates reacted strongly in the ELISA, as did two equine sera raised against EAV vaccines, indicating that the viral epitope was conserved between the viruses tested. Following vaccination with an inactivated whole virus vaccine, antibody detected with the recombinant antigen ELISA preceded the development of a virus-neutralizing response. The study demonstrates the potential application of rGL 55-98 as a diagnostic antigen.

Development and evaluation of ELISA procedures to detect antibodies against the major envelope protein (G(L)) of equine arteritis virus.

Enzyme-linked immunosorbant assays (ELISAs) were developed for the detection of antibodies against the major envelope glycoprotein (G(L)) of equine arteritis virus (EAV). A 6-Histidine tagged recombinant protein expressing the complete G(L) ectodomain (G(L)-6His), a glutathione-S-transferase recombinant protein expressing amino acids 55-98 of G(L) (G(L)-GST) and an ovalbumin-conjugated synthetic peptide representing amino acids 81-106 of G(L) (G(L)-OVA) were used as diagnostic antigens. An ELISA procedure was developed and optimised for each antigen. The G(L)-OVA and G(L)-6His assays showed the greatest specificity while the G(L)-GST assay was slightly more sensitive that the G(L)-OVA and G(L)-6His assays; results based on the analysis of 50 virus neutralisation positive and 50 virus neutralisation negative sera. The G(L)-OVA ELISA was selected for further evaluation since it was simpler to use than ELISAs based on recombinant antigens and did not suffer from background reactivity. The final sensitivity and specificity of the G(L)-OVA ELISA were 96.75 and 95.6%, respectively, results based on the analysis of 400 virus neutralisation positive and 400 virus neutralisation negative sera. It also detected EAV antibody (100% efficiency) in seropositive shedding stallions and, in ponies infected experimentally with the UK93 isolate of EAV, the appearance of virus neutralising antibodies and G(L)-OVA ELISA-specific immunoglobulins coincided.

Equine influenza vaccine efficacy: the significance of antigenic variation.

To investigate the level of cross-protection induced by equine influenza H3N8 vaccines derived from different lineages, two studies have been carried out with ponies vaccinated with 'American-like' and 'European-like' vaccines and experimentally challenged with a European-like strain. The results demonstrated that equine influenza vaccines clearly protect against challenge with homologous virus if serum antibody titres are sufficiently high. On the other hand, protection is incomplete even when animals vaccinated with heterologous strains have comparative antibody levels. Nevertheless, the protection afforded by heterologous viruses can be improved by stimulating high levels of antibody. It would be advisable to update equine influenza vaccine strains regularly so that they contain similar strains to variants that are circulating in the field.

Equine strangles modelled in mice.

Small animal models of Streptococcus equi infection have been confined to parenteral injection of mice which subsequently develop a septicaemia. To devise a model of infection more closely resembling strangles, 4.9 x 10(6) cfu of S. equi were placed on the nares of C3H and Balb/c mice (fifteen of each). Compared with ten uninfected controls, infected mice sneezed more often and their daily weight gain was significantly reduced. Histopathological examination seven days after infection revealed varying degrees of nasopharyngeal and regional lymphoid pathology in twenty two mice. Eleven mice had an early or mild rhinitis in which the nasal epithelium presented microabscesses containing polymorphonuclear leucocytes. Another eleven mice had a suppurative rhinitis or pharyngitis associated in most with regional lymphadenitis; in two mice, abscessated lymph nodes had erupted into perinodal connective tissues. Two mice had a vestibular abscess. The suppurative rhinitis was associated with extensive necrosis of nasal propria which occasionally extended to conchal bone, resulting in osteomyelitis. Multiple bacterial abscesses were seen in the spleen of one mouse. Histological lesions were not detected in control mice or in eight infected mice. S. equi was re-isolated from the nares of fourteen of the twenty two affected mice but not from the eight unaffected challenged mice or control mice. The close resemblance of this model to strangles in horses may justify its further use for the investigation of pathogenesis and protective immunity.

Antibody isotype responses in the serum and respiratory tract to primary and secondary infections with equine influenza virus (H3N8).

Serum antibody (IgGab, IgM and IgA) responses to primary and secondary infection with influenza A/equine/Newmarket/79 (H3N8) by nebulised aerosol were compared with local (nasopharyngeal and tracheal) antibody responses in ponies. Circulating IgGab antibody was of long duration after primary infection, whereas IgM responses were short-lived after both primary and secondary infections. The antigenic stimulation of secondary infection with equine influenza was sufficient to induce elevations of serum IgM and IgA in the presence of high levels of circulating IgGab. These results support the potential of virus-specific IgM measurement for the detection of recent exposure to virus in horses which have high levels of circulating IgGab. Unlike serum IgGab, nasal and tracheal wash antibody of this isotype did not show long duration after primary infection, but local antibody memory was demonstrated by anamnestic responses on rechallenge. Nasopharyngeal IgA developed later than IgGab and IgM, and was more durable.

The effects of vaccination with tissue culture-derived viral vaccines on detection of antibodies to equine arteritis virus by enzyme-linked immunosorbent assay (ELISA).

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of serum antibodies to equine arteritis virus (EAV). Results from this assay produced a good correlation with results from virus neutralisation tests in horses which had not been regularly vaccinated with commercially available mammalian tissue culture-derived viral vaccines. Vaccination of some horses with tissue culture-derived vaccines induced the formation of antibodies to bovine serum. These antibodies reacted with the bovine protein contaminants in the EAV ELISA antigen, producing false-positive results. Non-viral protein contaminants were found to be closely associated with EAV in that they co-purified with the virus during gradient centrifugation.

Cell mediated immune responses in ponies following infection with equine influenza virus (H3N8): the influence of induction culture conditions on the properties of cytotoxic effector cells.

Cytotoxic cell precursors and/or cytotoxic memory cells were demonstrated in the peripheral blood of ponies after aerosol infection with influenza A/equine/Newmarket/79 (H3N8). In order to reveal their cytotoxic potential, peripheral blood mononuclear cells required a secondary antigenic stimulation. In vitro induced cytotoxic cells showed activity against influenza infected target cells in a 3-4 h 51Cr-release assay. The reactivity of cytotoxic cells was markedly influenced by the conditions of the secondary induction culture. If high concentrations of exogenous crude equine IL-2 were used, virus infected target cells were susceptible to lysis by autologous or allogeneic effector cells. However, if IL-2 concentration was reduced, cytotoxic cells were generated which showed features consistent with cytotoxic T cells in that target-cell killing was genetically restricted.